Vertex Pharmaceuticals Inc. CEO Jeffrey M. Leiden saw his total compensation drop 38 percent to $17.4 million last year, largely on a steep cut in his stock-option awards from the Boston-based biotech. It was the second year in a row that Leiden’s pay declined from a 2014 payout of $36.6 million that made him the highest-paid head of a Massachusetts public company and sparked some shareholder criticism...